Agitator apparatus



Jan. 23, 1968- D. c; CHRISTENSEN AGITATOR APPARATUS Filed Oct. 7. 1966FIG.

lNVE/VTOR D. C. CHRISTENSEN 364.4,? '1 @"W,

FIG. 2

A T TOR/VEYS United States Patent 3,365,176 AGITATOR APPARATUS Don C.Christensen, Bartlesville, Okla, assignor to Phillips Petroleum Company,a corporation of Delaware Filed Oct. 7, 1966, Ser. No. 585,201 4 Claims.(Cl. 259107) ABSTRACT OF THE DISCLOSURE Agitator comprising a shellmeans and at least one impelling means rotatably mounted therein whichis adapted to produce laminar flow along the inner surface of the shellmeans in one direction and through a central portion of the shell meansin the opposite direction.

This invention relates to an agitator apparatus.

In another aspect, the invention relates to an agitator apparatuscomprising, in combination, a shell means, and at least one impellingmeans rotatably mounted therein which is adapted to produce laminar flowalong the inner surface of the shell means in one direction, and througha central portion of the shell means in the opposite direction.

In another aspect, the invention relates to the agitator apparatusdescribed above in which the impelling means has at least two bladeportions having an angle of about 90 between them, the first of which ispitched 45 from the horizontal axis of the impelling means; theimpelling means further comprises means adapted to receive rotatingmeans for the impeller.

In still another aspect, the invention relates to the agitator apparatusdescribed above, and comprises at least two impelling means having heatexchange means be tween them.

In another of its aspects, the invention relates to the agitatorapparatus described above wherein the shell means is substantiallycylindrical in shape, and is vertically disposed.

Agitator apparatus heretofore available have proven unsatisfactorybecause of the high turbulence produced in such devices. This problem isparticularly acute when the material being mixed is highly viscousbecause much power is wasted in driving impelling means which produceturbulent mixing in such systems. It is an object of this invention toprovide an apparatus which produces thorough, non-turbulent mixing. itis also an object of this invention to provide a mixing apparatus whichproduces laminar flow therewithin, thus reducing turbulence andconcomitant power wastage. A further object of the invention is toprovide an agitator apparatus especially suitable for mixing viscousmixtures uniformly, while subjecting the mixtures to heat exchange at ahigh rate of efficiency. It is a particular object of the invention toprovide an agitator apparatus that is especially suitable for viscoussystems having viscosity of 1000 cps. and higher uniformly and at a highrate of heat exchange.

Other aspects, objects, and the several advantages of the invention willbe apparent to one skilled in the art upon studying the specification,claims, and drawings.

According to the invention, an agitator apparatus is provided whichcomprises, in combination, a shell means, and at least one impellingmeans rotatably mounted therein Which is adapted to produce laminar flowon the inner surface of the shell means in one direction, and through acentral portion of the shell means in the opposite direction.

The agitator apparatus of this invention can be used to mix any system,but is particularly suitable for mixing viscous materials havingviscosities in excess, for example, of 1000 cps. The laminar flowproduced in the apparatus 3,365,176 Eatented Jan. 23, 1968 permitshighly efficient heat exchange when the heat exchange means areincorporated into the apparatus. Such means can be mounted in theapparatus in any suitable fashion such as, for example, by mountingheating or cooling coil between the impelling means normal to the flowof material in the apparatus. In a presently preferred embodiment, asshown in FIGURE 1 of the drawings, cooling or heating coils in the shapeof a spiral are mounted between the impelling means. Such coils insureefficient heat exchange without disturbing the laminar flow of thematerial through the apparatus.

The shell means of the invention can be of any desired shape anddimensions, and can be disposed at any desired angle of orientation. Forexample, the shell means can be spherical, cylindrical, conical, etc.,and can be disposed vertically, horizontally, or at any suitable anglewith the horizontal or vertical.

As described above, the impelling means is adapted to produce laminarflow within the shell means along the inner surface thereof in onedirection, and through a central portion of the shell means in theopposite direction. In one embodiment, the impelling means has at leasttwo blade portions having an angle of about therebetween, the first ofsaid portions being pitched 45 from the horizontal axis of the impeller.Further, the impeller further comprises means adapted to receiverotating means therein. As shown in FIGURE 1, a suitable impeller has atleast two blade portions having a 90 angle between them on both sides ofthe means adapted to receive the rotating means, and the blade portionsand means adapted to receive rotating means are integral. However, it isapparent that there can be any number of groups of two blade portionshaving a 90 angle therebetween, and that these portions need not beintegral with one another. Generally, the surface of each blade portionWill be planar, and the length, width, and pitch of each portion can besuitably varied in accordance with the type of material to be mixed,shape and dimensions of the shell means, the presence or. absence ofheat exchange means, and so on. Thus, it is apparent that the first ofeach group of two blade portions can be pitched 45 from the horizontalaxis in all four quadrants.

The impelling means of this apparatus are rotatably mounted therein in acentral portion thereof. As shown in FIGURE 1 of the drawings, theimpelling means can be fixedly attached to a shaft which extends throughthe shell means, and is driven by any suitable means such as a motor.However, depending upon the shape of the shell means, the dimensionsthereof, the composition of the system to be mixed, presence or absenceof heat exchange means and the type used and so on, the impelling meanscan be offset from the center of the shell means, and need not befixedly attached to a shaft. 'For the apparatus shown in FIGURE 1,speeds of from about 5 to about 50 revolutions per minute aresatisfactory.

Among the applications for which the apparatus of my invention hasadvantages are: polymerization reactions wherein a monomer ispolymerized to form a viscous solution of polymer in a solvent such aspolybutadiene, polyethylene, polypropylene, polystyrene, etc.; heatingor cooling viscous solutions such as molasses, heavy oils, the polymersolutions mentioned previously, etc.

Referring now to the drawings:

FIGURE 1 shows one embodiment of the apparatus of this invention, and

FIGURE 2 shows an end view of a single impelling means used in theapparatus of FIGURE 1.

In FIGURE 1, substantially cylindrical shell means 1 houses drive shaft2, to which a plurality of impeller means 4 are fixedly attached. Above,below, and between the impelling means 4 are heat exchange coils 6. Eachimpelling means has two portions on both sides of the shaft; the firstof the portions is pitched 45 from the horizontal axis of the impeller,and the second portion is pitched 90 from the first portion. Rotation ofshaft 2 and impelling means 4, which are driven by driving means 7,promotes ilow of a mixture upward along the inner surface of the shellmeans, and downward through the central portion thereof. Rotation ofshaft 2 in the opposite direction promotes flow upward in the centralportion of the vessel and downward along the inner surface of the shell.While the blades are shown pitched 45 from the horizontal, other anglesof pitch may be used. For example, each blade may be pitched 30 from thehorizontal in which case the angle between the two blades wil be 120. Itmight also be desirable to pitch the two portions of a blade atdifferent angles from the horizontal. This is the case in very largevessels Where the peripheral speed of the outer portion of the blade isconsiderably higher than that of the inner portion. In order to balancethe iflo-ws in such large vessels, it may be desirable to pitch theouter portion of the blade at an angle of 30 from the horizontal and topitch the inner portion at an angle of 45 from the horizontal.

FIGURE 2 shows, from an end view, the pitch of two blade portions 5 and6. Blade portion 5 is pitched 45 from the horizontal axis of theimpeller, and blade portion 6 is pitched 90 from the blade portion 5. Asmentioned above, rotation of such impelling means within a shell meanstends to promote flow along the inner surface of the shell means in onedirection, and through a central portion of the shell means in theopposite direction.

Reason-able modification and variation are possible within the spiritand scope of the invention, the essence of which is an agitatorapparatus comprising a shell means and at least one impelling meansrotatably mounted therein, and adapted to produce laminar flow along theinner surface of the shell means in one direction, and through a centralportion thereof in the opposite direction.

I claim:

1. An agitator comprising, in combination,

(a) a shell means free of internal appurtenances, in-

cluding bafiles and other ilow guiding means,

(b) a drive shaft extending substantially the length of said shellmeans,

(c) a plurality of spaced impelling means attached to said shaft adaptedupon rotation of said shaft to produce laminar flow along the innersurface of said shell means in one direction and through a centralportion of said shell means in the opposite direction, each of saidimpelling means extending from said shaft into close proximity to theinner wall of said shell and wherein the impelling means have at leasttwo blade portions having an angle of about degrees therebetween, thefirst of said portions being pitched at an acute angle from thehorizontal axis of said impelling means, and

(6.) heat exchange means extending into said shell means between atleast two of said spaced irnpelling means, said heat exchange meansbeing so shaped and arranged as to not impair the laminar flow producedby the impelling means.

2. An apparatus in accordance with claim 1 further characterized in thatthe first of said portions is pitched 45 degrees from the original axisof said impelling means and wherein said spaced impelling means arearranged in pairs and extend in diametrically opposite directions fromone another toward the shell.

3. An apparatus according to claim '-1 further characterized in that (a)is a vertically disposed enclosed cylindrical shell means and (b) is acoaxial drive shaft.

4. An apparatus according to claim 1 further characterized in that (d)is a tubular heat exchange coil mounted between the im-pelling meansnormal to the flow of material in the apparatus.

References Cited UNITED STATES PATENTS 1,945,436 1/1934- Keeney et a1.259-l07 X 1,958,118 5/1934 Szegari 259- 1,961,903 6/1934 McKee 259-97 X2,727,884 12/1955 McDonald 259107 X FOREIGN PATENTS 86,502 4/1896Germany.

ROBERT W. JENKINS, Primary Examiner.

